An Online Epilepsy Self-Management Tool for Patients With Epilepsy: A Formative Usability Study.

Personal space is regulated through proxemics, with Hall describing four distance zones—intimate (0 to 0.45 m), personal (0.45 to 1.2 m), social (1.2 to 3.6 m), and public (greater than 3.6 m)—and emphasizing that preferred spacing depends on situation and culture (). In everyday human-human interaction (HHI) during navigation, these preferences are maintained through anticipatory adjustments: People begin to deflect, reorient, or subtly modulate speed before close approach based on predictions of others’ future motion (–). Prior work modeled pairwise encounters with intended-path updates and reported simple anchors for everyday avoidance: At the closest point of passing, pedestrians typically keep about 0.75 m of distance, and, immediately after passing, they tend to widen the side-by-side gap to at least about 0.8 m (). Service robots increasingly share these pedestrian-centered spaces, from delivery platforms and cleaning units to personal mobility vehicles (PMVs). Services already available to the public include an autonomous mobility service by WHILL at Narita International Airport, where autonomous PMVs support passenger transfers in departure areas (). As populations age, the number of people with reduced mobility increases, strengthening the case for such assistance in public spaces and transport hubs (). In this context, acceptance and effectiveness depend on how comfortably robots share space with people; measuring when human-robot interaction (HRI) proximities align with or diverge from HHI norms is especially important for PMVs that approach, travel alongside, and, sometimes, dock near people at close range. Within HRI, initial-encounter studies have examined comfortable distances around a mechanical-looking platform and factors that can influence them. One study reported that many adults stopped in Hall’s personal zone and children in the social zone, with substantial individual variability (). Follow-up work found that a synthesized robotic voice was associated with slightly larger approach distances than natural voices and that prior exposure to the robot reduced standoff distance (). Complementary evidence points to roles for approach direction, speed, and gaze, indicating that context, communicative cues, and familiarity can modulate HRI spacing. Consequently, measured distances may vary across settings, instructions, and prior experience. A recent review and meta-analysis of 27 HRI studies concluded that several frequently discussed moderators, including gender, coarse appearance class, and whether the human or the robot initiated the approach, showed small or inconsistent overall effects, and it called for theory-led, higher-powered studies with better coverage of environmental factors such as crowding and density ().